1. Field of the Invention
This invention relates to a new recording liquid and, more particularly, to a recording liquid suitable for a recording system in which droplets of the recording liquid are jetted from a small jet (jet orifice) provided at a recording head and the image is printed on a surface of a recording material.
2. Description of the prior art
Writing materials (such as a fountain pen, felt pen and the like) which make records on recording materials such as paper and the like usually use an ink composed of various dyes dissolved in water or organic solvents.
There are also known compositions composed of various dyes into water or other organic solvents and the like used in the ink jet recording system which records by jetting liquid within the recording head from the jet orifice with vibration by a piezo-oscillator or with electrostatic attractive force and the like by high voltage apply. But, compared with ink for writing materials such as a popular fountain pen, felt pen and the like, the recording liqiud for the ink jet requires more strict conditions as to many characteristics.
Such the ink jet recording method is that the recording was carried out by jetting droplets of the recording liquid, the so-called ink, and adhering this jetting ink to a record-receiving member. The recording liquid is comprised of a recording agent (using dye or pigment) and a liquid medium (water, various organic solvents, or a mixture thereof) capable of solving or dispersing the recording agent, as basic components, and if desired, various additive agents are added.
In such a recording method, there are various systems depending methods for generating droplets and methods for controlling the jet direction. An example of system is shown in FIG. 1.
FIG. 1 shows an apparatus in which a recording signal is applied to a recording head part containing the piezo-oscillator and droplets of the recording liquid are generated to effect recording in response to the signal. In FIG. 1, the recording head is designated by 1, the piezo-oscillator by 2a an oscillating plate by 2b, an inlet of ink by 3, a liquid chamber in the head by 4 and a liquid jetting portion (jetting orifice) by 5. Recording liquid 7 is introduced into the liquid chamber 4 from a storage tank 6 through a supply tube 8. In case of necessity, intermediate processing means 9 such as pump or filter may be provided in the supply tube 8. Recording signal S is converted into a pulse by signal processing means 10 such as a pulse converter and then applied to the piezo-oscillator 2a. Change in pressure on the recording liquid within the liquid chamber 4 caused by the signal results in droplets 11 of the recording liquid 7 being jetted through the jet orifice 5. Thus, an image is printed on the surface of the record-receiving member 12 with the droplets.
There are known various apparatuses other than the above mentioned apparatus. For example, FIG. 2, shows a modified embodiment of that in FIG. 1. In the modified embodiment, a liquid chamber 4 is a nozzle form, and around provided with a cylindrical piezo-oscillator (in this apparatus, a mechanism generating droplets is essentially the same as that (shown in FIG. 1). There are known an apparatus in which charged droplets are continuously generated to use a portion of the droplets for recording, another apparatus in which heat energy corresponding to a recording signal is applied to a recording liquid in a chamber of a recording head to generate droplets by the heat energy, and the like.
An embodiment is shown in FIGS. 3-a, 3-b and 4.
A head 13 is manufactured by jointing a plate such as glass, cermics, plastics, and the like, having a groove 14 to a head-generating head 15 used for a heat-sensitive recording process (A thin film head is shown in the Figs., however a heat-generating head is not restricted to this construction). The heat-generating head 15 is constituted of a protective film 16 made of silicon oxide and the like, aluminum electrodes 17-1 and 17-2, a resistive heater layer 18 made of nichrome and the like, a heat-accumulating layer 19, and a substrate 20 having an excellent heat-releasing property such as alumina and the like.
An ink 21 arrives at the jet orifice, so that a meniscus 23 is formed by a pressure P.
When an electric signal is applied to electrodes 17-1 and 17-2, heat is rapidly generated at the region indicated by "n" in the heat generating head 15, and a bubble is formed in ink 21 contacting the "n" region.
The pressure due to the formation of the bubble projects the meniscus 23 and a recording droplet of ink 21 is ejected as a droplet 24 through an orifice 22 and projected to the record-receiving member 25.
FIG. 4 is a schematic diagram of multi-head made of a plurality of heads as shown in FIG. 3-a. The multi-head is fabricated by adhering a glass plate 27 provided with multi-groove 26 to the heat generating head 28 as illustrated in FIG. 3-a.
FIG. 3-a is a schematic cross sectional view of the head 13 taken along the ink flow path while FIG. 3-b is a schematic cross sectional view of FIG. 3-a taken along the A-B line.
In the past, there are known the recording liquid in which various dyes and pigments were dissolved and dispersed in aqueous or nonaqueous solvent, for example, as shown in Japanese Patent Publication Nos. 8361/1975, 40484/1976, 13126/1977, and 13127/1977, and Japanese Patent Laid Open No. 95008/1975. Desirable conditions for such recording liquid are shown as follow.
(1) Having a property of liquid (viscosity, surface tension, conductivity and the like) matched to jet conditions (actuation voltage of piezoelectric device, actuation frequency, shape and quality of material of the orifice, diameter of the orifice and the like).
(2) Not clogging the minute jet orifice and hole of a capillary because long time storge property is very good.
(3) Fixation to the record receiving members (paper, film and the like) can proceed rapidly, circumference of a dot is smooth, and the blur is little.
(4) A color tone of the printed image is sharp and the density is high.
(5) Water resisting property and light fastness of the printed image are excellent.
(6) Not corroding materials for handling the recording liquid (vessel, joint tube, seal materials and the like).
(7) Safety to a bad smell, toxicity, inflammability and the like is excellent.
It is very difficult to satisfy above mentioned conditions at the same time. In this point, the above-mentioned prior art is not satisfactory.
Since the recording liquid is composed basically of dye and the solvent, the above mentioned properties of recording liquid are determined by matching of dye to solvent. Therefore, it is very important in the field of the art to effect matching of dye to solvent compositions so as to have the above-mentioned properties in the recording liquid.